Network Support for Multicast Video Distribution
Calvert, Kenneth L.
Zegura, Ellen W.
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Multicast video distribution in a best-effort environment presents challenges to system designers, including heterogeneity in the bandwidth availability on the paths from the sender to the receivers and dynamic behavior in the network and set of receivers over time. Classic approaches to dealing with dynamic conditions involve adaptation at the sender (for unicast) and adaptation driven by the receivers (for multicast). Both approaches have limitations that affect the quality of video received. In this paper, we consider a third option for the location of adaptation, namely: in the network. We demonstrate that a modest amount of state and computation at network routers can yield significant performance gains for multicast video distribution. Our schemes maintain the advantages of receiver-based adaptation, while overcoming the limitation. Since the network applies the adaptation, the time and place for adaptation can better match network conditions. Further, the adaptation can occur more rapidly, without the need for route changes. Finally, the adaptation can occur at finer granularity, providing better quality and more graceful degradation to receivers.